As a method for producing a power module, such as an inverter device, etc., there is known a power module production method, wherein a semiconductor chip is first soldered to a heat sink, and the heat sink and a cooler are then bonded by thermal compression with an insulating resin sheet interposed between the heat sink and the cooler (see, for example, Patent Literature 1).
FIG. 3 is a schematic view illustrating a conventional power module production method. First, as shown in FIG. 3(a), a semiconductor chip 101 is soldered to a heat sink block 102 (soldering step). The heat sink block 102 comprises a plate-shaped member that is larger than the semiconductor chip 101, and the semiconductor chip 101 is soldered at an approximately central location on one side thereof. Soldering is performed through, for example, solder reflow, wherein the semiconductor chip 101 and the heat sink block 102 as a whole are evenly heated (overall heating) to the melting temperature of the solder within a reflow oven.
Next, as shown in FIG. 3(b), a step of bonding the heat sink block 102 to a cooler 104 by thermal compression (thermal compression bonding step) is performed with an insulating resin sheet 103 interposed between the heat sink block 102 and the cooler 104. The insulating resin sheet 103 comprises a sheet-shaped member that is larger than the heat sink block 102, and the heat sink block 102 is bonded at approximately the center of the insulating resin sheet 103 by thermal compression. Thermal compression bonding is performed by pressing the heat sink block 102 and the lateral portions of the insulating resin sheet 103 that protrude sideways from the heat sink block 102 against the cooler 104 under heated conditions.
Then, as shown in FIG. 3(c), the semiconductor chip 101 and terminals are connected with a wire 105 (wire bonding step), and a step of burying the semiconductor chip 101 within a housing 107 by means of an encapsulation material 106 (molding step) is performed.